EP-0,196,132 discloses an oral solution containing a 1,2-benzisoxazol-3-yl derivative, methylparaben, propylparaben, tartaric acid, Na-saccharin, raspberry and gooseberry essence, and the polyhydric alcohols sorbitol and glycerol (1,2,3-propanetriol). Comparable solutions wherein the benzisoxazole derivative was risperidone, however, were found to exhibit an unsatisfactory physicochemical stability. Unexpectedly, sorbitol was found to cause decomposition of risperidone upon storage of the solution at elevated temperatures, i.e. under conditions which imitate those of a long storage time. A physicochemically stable risperidone solution was obtained after omitting the sorbitol constituent from the composition.